The invention relates to a stud gun or stud driver by means of which fasteners, as a rule in the form of a nail or stud, can be driven into place. The stud driver contains a propelling piston driven by the propellant gas discharge on ignition of the cartridge, the forward movement of the piston driving the stud into place.
It is particularly in the case of automated operation of such a stud driver in which the fasteners to be driven into place are supplied by means of a crib incorporated in the driver that it is desirable to automatically return the propelling piston to its starting position.
A stud driver of this kind is already known (U.S. Pat. No. 3,331,546) in which for this purpose a plurality of disk springs is arranged about a piston rod of a propelling piston. These disk springs are preferably made of polyurethane and arranged alternatively reversed so that a pack of disk springs materializes, each of which is not connected to the other.